Thermostatic control for electric circuits



y 93 G. L. COLBIE 1,959,659

THERMOSTATIC CONTROL FOR ELECTRIC CIRCUITS Filed Dec. 30. 1930 IIIIIIIIIIIIII I I A /0 Q95 1. 99%; i Y

ATTORNEY Patented May 22, 1934 UNITED STATES PATENT OFFICE THERMOSTATIC CONTROL FOR ELECTRIC CIRCUITS Gus L. Colbie, Brooklyn, N. Y., assignor to Hudson Electric Heating Corporation, New York, N. Y., a corporation of New York Application December 30, 1930, Serial No. 505,537

4 Claims. (01. 200-139) My invention relates to an improved method cuit breaker has in engagement with its periphof thermostatic control for electric circuits, and cry a pair of metallic wipers each of which is comprises (in the form here illustrated) certain connected with an electrical line leading to cerimprovements on the type of thermostatic aptain electrical devices to be controlled such as g paratus shown in U. S. Patent No. 1,762,174, to the motor on an oil burner, a blower for a house 60 5 gaged by oppositely disposed pawls which are portions 36, the spacing of which is designed to Emil F. Holinger, dated June th; 1930. heating furnace, or for oven-heat control. The One object of my invention is to simplify the periphery of the circuit breaker is arranged with structure and provide a more positive action to alternate metal and insulating contacting surthe operating parts. faces and the wipers are adapted to engage 10 Another object is to provide a curved or either two metal surfaces or two insulating surarcuate bi-metallic element which responds faces during each partial rotation of the ratchet quickly to temperature changes and permits the wheel a distance of one-half a tooth. When placement of operating members within a conthe bi-metallic member is expanded by heat, fined area thereby providing a thermostatic unit and the ratchet wheel is rotated through onewhich is adaptable for many uses. half a tooth, the circuit breaker attached there- Another object is to provide an internal ad to would move through a distance of one tooth justment for the bi-metallic member for certain to break the electrical circuit and on cooling, broad predetermined temperature ranges and an the bi-metallic element approaching its normal external adjustment for varying the original adposition would cause the ratchet wheel to rotate justment and control the temperature within through the distance of another half tooth, by

said broad range. the action of the opposite pawl, while the cir- Another object is to provide a circuit breaker cuit breaker rotates through a distance of one which breaks the electrical contact across two full tooth to permit the contact wipers to enterminals. gage the metal surfaces and complete the elec- These and other features are set forth in the trical circuit.

following specification and drawing, wherein: In Fig. 1, I have shown a housing 10, in which Figure 1 is a front view of my device with the is contained the thermostatic control apparatus cover of the casing removed; designated generally by the reference charac- Fig. 2 is a vertical central section taken on ter 12. the line 2-2 of Fig. 1, showing the casing at- A horizontally disposed shaft 14 having an entached to the wall of a room; larged outer end 16 is riveted at its inner end to Fig, 3 is a rear view of the casing; the back wall of the casing 10 at 18, and has Fig. 4 is a front view of a portion of the casing mounted thereon a ratchet wheel 20. The ratchet and cover showing the external adjusting lever; wheel 20 comprises ratchet teeth 22, a shoulder 24, and and a reduced hub 26, the whole being confined Fig. 5 is a view similar to Fig. 1 of the opbetween the edge of ashoulder 15, on the shaft 14, crating parts, showing said parts in operating and the inside surface of the back wall of the position with the ratchet actuating pawl and casing 10. contact terminal wipers in a position just prior A rotary circuit breaker 28, comprising a metalto engagement with the next following teeth of he disc 30 imbe-dded in an insulating disc 32, is 9 ratchet and circuit breaker wheel. passed over the hub 26 of the ratchet wheel 20 a Briefly, my improved device comprises a and secured to the shoulder 24 of said ratchet ratchet wheel having a rotary circuit breaker wheel by means of pins 34. The periphery of the attached thereto, said ratchet wheel being en circuit breaker has equally spaced tooth shaped secured to the free moving end of a substantially have two teeth on the circuit breaker equal to one inverted U-shaped bi-metallic element. At ceron the ratchet wheel, as indicated by the broken tain predetermined temperatures, the free end radial lines AA. The tooth shaped portions 36 of the bi-metallic element is moved outward or are adapted to be engaged by a pair of tensioned inward when heated or cooled, and one of the electrical contact wipers 38 and are arranged so ratchet operating pawls rotates said ratchet that said wipers 38 will engage either two metal wheel through a distance of one-half a tooth, surfaces 40 or two insulating surfaces 42 at the the opposite pawl sliding over a whole tooth same time. To prevent sparking or any reverse due to the movement of the ratchet wheel and rotation of the ratchet, a beveled edge 44 is pro- 55 the latter pawl in opposite direction. The cirvided on each of the insulating teeth 42 at the O1 oven temperature.

point where the wipers 38 snap off the edge of each metallic tooth.

An insulating support member 46 is secured to the rear wall of the casing 10 and has mounted. thereon the two contact wipers 38, each of which has fastening ears 48 formed at right, angles to the wiper blades 38 and has openings 50 through which bolts 52 are inserted. Nuts 53 fit over the threaded ends of bolts 52, engaging the ears 48; and two lead-in electrical contact Wires 54 are. secured to the ears 48 in any convenient way.

A bi-metallic thermostatic element fail-having at substantially inverted U-shape is mounted withinthe casing 10. One end 58 having an opening 68 is slipped over an inwardly disposed stud -62,,said: stud being mounted in a bearing 64 formedin tegrally with the casing 10. The end 58 is held in a fixed position by meansof a-coil spring 56 positioned around the inside projection of the bearing 64 and engaging the outer surface of the end. 58,. and a nut 68- whioh is screwed on the threaded end 70 of thestud-62 engagingthe inner surface of said end 58'. A cotter. pin 67- engages slots 69 in the nut and aslot '71 in the stud 62.

The oppositeend 72. ofthe bi-metallio element 56 is free to move along. an inwardly disposed? guide pin 74 secured to the casing; 10, said: pinengaging an openingflfi inthe end" 72;, A spring metal: strip 78- is formed. with two. inwardly disiposed' arms 80,81, and issecuredtotheend 720i" said lei-metallic; element;- 56'. The ends: of the. arms 80, 81 are formedv into pawls 82,.83;v which are adapted to engage thefteeth 22:0f. the ratchet wheel 20; The upper. pawl 82'is'bent so thatLits. lower'surface engages'the surface'ofa tooth along the upperportion of said ratchet'wheel', while the lower pawl 83=is adaptedto engagea tooth on the opposite or. lower portion. The lower arm 81 has a slot 84 cut through it to provide. clearance for the teeth22;

Certain. specific settings of mean. temperature may be made which will. vary: according to the use of the said thermostat; for instance, if the thermostat is to. be used for room temperature the mean temperature would probably be 70 grees, or if used in oven heat-control the average mean temperature would approximate say 300' degrees; An initial factory setting is made to=ffx the position of the bi-metallic member for either a mean room temperature, or-amean-oven temperature, and additional means is provided to make external adjustments todeter-mine a working range of operation. 1

To make theinitial factory setting; the end 58 r of the bi-metallic element is adjusted (at room temperature if the thermostat is to be used in ahouse heating system) along the stud 62 by the nut 68 sothat the edges 86 and 87 of the pawls 82 and 83 are in engagement with-the working. face of the ratchet teeth 22,,and any movement on the part of thefree end of said br-m'etallic element will cause the ratchet wheel to rotate;

When the thermostatis to be used to control room temperature; the range wouldprobably be between 65 and degrees, whereas the temperature range for oven heat control. would be between 200 and 500 degrees. The initial factory setting of the bi-metallic element would differ according as it is to be used forcontrollingroom The positions shown in the drawing would bezcorrect for room' temperature control, but for oven control the'inner f'ace 750i. the pawl strip 78 securedto the free end-"12 of the bi-metallic'element'would'engage the shoulder 77 on. the pin'74 withenoughtension to allow the temperature to rise to about 150 degrees before the said free end moves outward. If desired, bimetallic elements of different dimensions may be provided at the factory for each condition instead of varying the position of one element.

The external means for adjusting the initial setting consists of a lever 88 fixed to the-stud 62, mounted outside of the casing 10 on the outer extension of the bearing 64, which is adapted to be rotated through an angle of about 90 and provide a longitudinal movement to the stud 62 and the-end 58: of the bi-metallic element in an outward or inward direction. The lever 88 comprises. a fiat portion8'7 having an inwardly disposed. upper portion 90, the corners 92 and 93 of which: are adapted to contact with the cover 94 to limit the movement of said lever about its pivot" 95: Atthe lower end of said lever 88 is an inwardly. disposed lug 9'7 which is adapted to engage the periphery of the casing 10, and when thelever ismoved, thecurvature of saidperiphery provides a; camsurface which causes the lever 88=andr the stud 62 to be moved outward or inward. Since the; end 58" of: the lei-metallic: elem'ent' issecured to: the st-ud62- it moves. a dis-- tance equal to the movement isretained'in any inter-mediateposition by means of-thepressure-of the'spring 66 againstt-he'outer face of the bi-metallic end 58;

This. device is: particularly adapted for use: in

rooms: for controlling: the temperature same, 10- is provided with stamped, feet 96' which; are offset to hold. the

and therefore: the casing-1 casing. in spaced relation to the wall for aircirculation, the air passing through the openings 98: left; after stamping" and through: additional openings;99:. Holes 100: are provided to accommodate screws 102rwhen the casinglo is secured to-a wall;

The/operation. is. as follows:

Theposition of the parts as shown in Fig. l, with: the contact wipers in engagement with the metal contact-surfaceseo, indicate that. the room temperature is low and a circuit has been. completedltozthe heating deviceto supply additional heat; Asetherheat-z increases; the free endtof the bi-'metallic element expands or: moves outward carrying with it the pawls- -81; The; lower pawl 81' engagesthe working face: of: one ratchet tooth 22: causing the ratchet wheel? and circuit breaker to rotate slightly.v When the partsare' in the positionshewn inFig. 5, the desired temperature hasaaboutbeen reached, and the contact wipers are about-to snap off the surface. of the contact teeth to teeth to break the circuit of the heat supplying means. As the room is cooled, the free end 72 of the bi-metallic member returns to normal position and the ratchet wheel is rotated by'the upper pawl 80 until the contact wipers are brought into engagement with" another set of contactv surfaces to complete the circuit again. These operations are automatically repeated as the temperature changes.

Among the advantages of the invention may be mentioned the compact arrangement resulting'from the nesting of all the mechanism within the semi-circular, temperature responsive strip, the locating ofthe secondary temperature adjusting element outside of the casing, theproduction of a double break in the controlled circuit and theventila-ting back forthe thermostat casing produced bystamping out the feet 96; 96 from the back thereof.

Various changes could he. made inthe details of said stud and the surface of the insulating.

circuit breaking of construction herein shown and described without departing from the essence of my invention so long as the above features of construction or operation, or some of them, are preserved.

Having described my invention, I claim:

1. In a thermostat the combination of a circuit breaking and making mechanism with a substantially semi-circular temperature responsive element having one free end adapted to actuate the circuit breaking mechanism, and one end mounted upon a longitudinally movable stud, means for adjusting said latter end along said stud for one adjustment and means for adjusting the stud for another adjustment.

2. In a thermostat having an element adapted to be varied in form by changes in its temperature, circuit breaking means operatively connected to one portion of said element and a cylindrical casing for the above described mechanism, an anchorage member projecting through the casing wall to which another portion of said temperature responsive element is connected, which anchorage member comprises a stud extending through a tubular bearing in said casing wall, together with a spring bearing in said casing wall, and tending to draw said stud into said casing, and a cam member mounted on the outwardly projecting end of said stud and bearing on the curved exterior of said casing, whereby, on swinging said cam member on said stud as an axis, the spring is flexed and the stud and attached portion of sai temperature responsive element moved radially of the casing.

3. In a thermostat, a circuit breaking and making mechanism and a casing enclosing same. in combination with a semi-circular temperature responsive element having one free end adapted to actuate the circuit breaking mechanism, and one end anchored on a stud freely mounted in a bearing on the casing wall extending inwardly thereof, an adjusting nut on said stud forming a stop for the anchored end of the temperature responsive element, a spring engaging the opposite surface of said temperature responsive element and a lever secured to a portion of said stud extending outside of said casing wall, whereby adjustments of the anchored end of the temperature responsive member can be made both inside and outside of said casing to vary the temperature ranges.

4. In a thermostat for controlling electrical circuits, the combination with a temperature responsive element mounted within a cylindrical casing, of an anchorage for one end of said temperature responsive element, means to adjust said end along said anchorage, a lever joined to the external end of said anchorage, having a portion thereof in engagement with the exterior of the casing wall and adapted when moved, to be cammed outward by its movement over said wall, whereby the said anchorage is given an external adjustment.

GUS L. COLBIE. 

